TOPIC: Graphs Fonts

I have search the forum to solve this and I have performed all action but I still can not fix this. My survey is in Greek and all characters are shown ok EXCEPT the graphs characters in the statistics.
I have put the arail.ttf in the fonts directory, I have set the arial.ttf in the config.php file with $chartfontfile = 'arial.ttf'; and still, as you can see in the attachment, I can not get them to display correctly. Any other ideas?
Thanks.

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I've cleaned all temporary folders (windows,user,limesurvey)
I've copyed arial.ttf, tahoma.ttf and verdana.ttf to /fonts folder in limesurvey.
I've changed chartfontfile from "auto" to those in config.php.
I've changed $this->setFontProperties("tahoma.ttf",8); to arial and verdana in classes\pchart\pchart\pChart.class
I've stopped and restarted Apache, and did not works.
Any other idea?
Thanks in advance.